JP2005175256A - Light receiving device, and light projecting/receiving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a light receiving device to appropriately detect light in a prescribed wavelength at a wide angle of view. <P>SOLUTION: A light receiving unit 20 comprises a light receiving element 22, and a light receiving optical system 21 for guiding light to the light receiving element 22. A band-pass filter 23 for transmitting light in a prescribed wavelength λ0 is inserted into the optical path of light received by the light receiving element 22. In the band-pass filter 23, the center wavelength of a light transmission band is set to a longer wavelength side than the prescribed wavelength λ0, and light transmittance that is equal to or more than a prescribed value is shown when light in the prescribed wavelength λ0 is incident vertically to the band-pass filter 23. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a technique for detecting light having a predetermined wavelength, and more particularly to a technique for detecting the predetermined wavelength using a bandpass filter.

  Conventionally, in a light projecting and receiving device configured to project light from a projector to a subject and detect reflected light from the subject with a light receiver, in order to reduce the influence of light from the surrounding environment (environmental light) Some light emitting devices use a semiconductor laser that can be regarded as a single wavelength as a light source, and a light receiving device includes various optical filters for cutting light other than wavelength components emitted from the semiconductor laser (for example, Patent Document 1). ). In this type of light projecting / receiving device, the light receiver may be provided with a band-pass filter that transmits the wavelength component emitted from the semiconductor laser.

JP-A-9-196632

  In general, an interference film type band-pass filter has a characteristic that a transmission wavelength is different depending on an incident angle of light. FIG. 10 is a diagram illustrating characteristics of the bandpass filter. Usually, a bandpass filter is designed by adjusting the transmittance of light incident perpendicular to the filter surface, and is most efficient when the wavelength λ0 to be detected is incident perpendicular to the filter surface. Designed to be transparent. Therefore, generally, the center wavelength of the light transmission band of the bandpass filter is formed so as to substantially coincide with the wavelength λ0 to be detected (characteristic curve T10 in FIG. 10).

  However, as the incident angle to the bandpass filter increases, the transmission wavelength of the bandpass filter gradually shifts to the short wavelength side as shown by characteristic curves T12, T13, and T14 in FIG. In the example of FIG. 10, the bandpass filter showing the characteristic curve T10 when the incident angle is 0 ° becomes the characteristic curve T11 when the incident angle is 10 °, and the characteristic curve T12 when the incident angle is 20 °. When the incident angle is 30 °, the characteristic curve T13 is obtained. For this reason, even if an attempt is made to detect light having a wavelength λ0 in the light receiver, if the incident angle of the light with respect to the bandpass filter exceeds 20 °, good detection cannot be performed, and the angle of view ( There was a problem that the viewing angle) could not be increased.

  Accordingly, the present invention has been made to solve the above-described problems, and its object is to provide a light receiver and a light projecting / receiving device capable of detecting light of a predetermined wavelength with a wide angle of view. To do.

  A light receiving device according to the present invention detects light of a predetermined wavelength, receives a light and performs photoelectric conversion, a light receiving optical system that guides incident light to the light receiving element, and the light receiving element receives light. A bandpass filter interposed in the optical path of the light to be transmitted, wherein the bandpass filter has a center wavelength of a light transmission band set longer than the predetermined wavelength, When the light is perpendicularly incident on the band-pass filter, the light transmittance is a predetermined value or more.

  In this light receiving device, the center wavelength of the bandpass filter is equal to or more than half of the wavelength shift amount of the bandpass filter that occurs when light of the predetermined wavelength is incident on the bandpass filter at a maximum incident angle, It is preferable to set so as to be on the long wavelength side.

  Moreover, it is preferable to set the half-value width of the band pass filter in the light receiving device to be larger than the wavelength shift amount.

  Further, the bandpass filter in the light receiving device is set such that the light transmittance for the predetermined wavelength increases as the incident angle when the light of the predetermined wavelength enters the bandpass filter increases. It is preferable.

  The light projecting and receiving device according to the present invention includes a projector that converts light having a predetermined wavelength emitted from a light source into a predetermined pattern light and projects the light onto a subject, and the subject on which the pattern light is projected by the light projector. And a light receiver that receives the reflected light of the reflected light by the light receiving element via the light receiving optical system. In the light receiver, a band is formed in the optical path until the reflected light is guided to the light receiving element. A pass filter is inserted, and in the band pass filter, the center wavelength of the light transmission band is set longer than the predetermined wavelength, and the reflected light of the predetermined wavelength is perpendicular to the band pass filter. It is characterized by showing a light transmittance of a predetermined value or more when incident.

  In this light projecting and receiving device, the center wavelength of the bandpass filter is equal to or greater than half the wavelength shift amount of the bandpass filter that occurs when light of the predetermined wavelength is incident on the bandpass filter at a maximum incident angle. It is preferable to set so as to be on the long wavelength side.

  Moreover, it is preferable to set the half-value width of the bandpass filter in the light projecting / receiving device to be larger than the wavelength shift amount.

  Further, the bandpass filter in the light projecting and receiving device is set so that the light transmittance for the predetermined wavelength increases as the incident angle when the light of the predetermined wavelength enters the bandpass filter increases. It is preferable.

  According to the present invention, the center wavelength of the bandpass filter inserted in the optical path of the light received by the light receiving element is set on the longer wavelength side than the predetermined wavelength, and light of the predetermined wavelength is applied to the bandpass filter. On the other hand, even if it is perpendicularly incident, it is set so as to show a light transmittance of a predetermined value or more. The light of a predetermined wavelength can be transmitted satisfactorily. Therefore, a light receiver and a light projecting / receiving device capable of detecting light of a predetermined wavelength with a wide angle of view can be realized.

  In addition, the center wavelength of the bandpass filter is set to be longer than the half of the wavelength shift amount of the bandpass filter that occurs when light of a predetermined wavelength is incident on the bandpass filter at the maximum incident angle. Accordingly, light having a predetermined wavelength incident at an arbitrary incident angle up to the maximum incident angle with respect to the bandpass filter can be transmitted favorably.

  In addition, by setting the half-width of the bandpass filter to be larger than the wavelength shift amount, the light having a predetermined wavelength incident on the bandpass filter at an arbitrary incident angle up to the maximum incident angle is increased. It can be transmitted with transmittance.

  Furthermore, by setting the bandpass filter so that the light transmittance for the predetermined wavelength gradually increases as the incident angle when light of the predetermined wavelength enters the bandpass filter increases, shading by the light receiving optical system is performed. Thus, even when the incident angles with respect to the band-pass filter are different, it is possible to detect light having a predetermined wavelength with a uniform light amount.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<First Embodiment>
FIG. 1 is a perspective view showing an overall configuration of a light projecting / receiving device 1 according to the present embodiment. The light projecting / receiving device 1 shown in FIG. 1 exemplifies a three-dimensional camera (range finder) that measures a three-dimensional shape of a subject 9 by slit light projection. The light projecting / receiving device 1 includes a light projector 10 and a light receiver 20. The light projector 10 emits, for example, a band-shaped light L 1 toward the subject 9, and the reflected light L 2 from the subject 9 is emitted from the light receiver 20. Detected. Then, the three-dimensional shape of the subject 9 can be obtained by detecting the distortion or the like of the belt-like portion W1 received by the light receiver 20. The projector 10 scans the strip light L1 in a direction perpendicular to the light distribution direction of the strip light L1, and the light receiver 20 detects the distortion of the light L2 at each scanning position, so that the object 9 A three-dimensional shape in a wide range may be obtained.

  In this light projecting / receiving device 1, in order to prevent light from the surrounding environment (environment light) from being detected by the light receiving device 20 and reducing the measurement accuracy, the light projecting / receiving device 1 has a narrow band wavelength that can be regarded as a single wavelength by the light projecting device 10. The light receiver 20 is configured to emit a certain amount of light, and is configured to satisfactorily detect the light component emitted from the projector 10 while reducing the influence of ambient light.

  FIG. 2 is a diagram illustrating an internal configuration of the light projecting / receiving device 1. The projector 10 includes a light source 11 that emits light for irradiating the subject 9, and a projection optical system 12 that converts the emitted light from the light source 11 into a strip-shaped light L 1 and projects it onto the subject 9. The

  The light source 11 includes, for example, a semiconductor laser that emits laser light having a predetermined wavelength λ0 that can be regarded as a single wavelength, an LED that emits light having a narrow band wavelength, and the like. In the present embodiment, the case where the wavelength λ0 of the light emitted from the light source 11 is 785 nm is exemplified.

  The projection optical system 12 includes a collimator lens that converts divergent light emitted from the light source 11 into parallel light, and a cylinder lens that converts parallel light emitted from the collimator lens into a strip-like light L1 as shown in FIG. It is prepared for. In addition, when the belt-like light L1 is scanned in a direction perpendicular to the belt-like light distribution direction, the belt-like light L1 further includes scanning means such as a galvanometer mirror or a polygon mirror for scanning the light L1 emitted from the cylinder lens. Configured.

  On the other hand, the light receiver 20 includes a light receiving optical system 21, a light receiving element 22, and a band pass filter 23. The light receiving optical system 21 forms an image of the reflected light L2 from the subject 9 on the light receiving surface of the light receiving element 22. The light receiving element 22 has, for example, a structure in which a plurality of pixels are two-dimensionally arranged on a light receiving surface like a CCD area sensor, etc., performs photoelectric conversion in each pixel, and outputs an electric signal corresponding to the amount of received light for each pixel. Output. Further, a band pass filter 23 is attached to the light receiving surface of the light receiving element 22, and the light receiving element 22 receives only light having a wavelength component transmitted by the band pass filter 23. The bandpass filter 23 is an interference film type optical filter, and is disposed perpendicular to the optical axis.

  In general, an interference film type optical filter is formed such that a thin film is coated on a glass substrate and only a wavelength in a specific band is transmitted using interference in the thin film. Therefore, the light transmission band can be set to an arbitrary state by adjusting the number of layers of the thin film formed on the substrate, the refractive index, and the like. In the present embodiment, even when a wavelength shift occurs due to an increase in the incident angle of the reflected light L2 incident on the light receiver 20, the light component having the predetermined wavelength λ0 emitted from the light source 11 is satisfactorily transmitted. A band pass filter 23 that can be detected by the light receiving element 22 is used.

  FIG. 3 is a diagram illustrating light incident on the light receiver 20. The light La parallel to the optical axis is incident on the bandpass filter 23 perpendicularly (incidence angle 0 °). On the other hand, the light Lb incident on the light receiver 20 is incident on the bandpass filter 23 at an incident angle θ (θ> 0 °) because it is incident from the peripheral portion of the visual field range of the light receiver 20.

  FIG. 4 is a diagram illustrating the wavelength shift of the bandpass filter. For example, when the light La is perpendicularly incident on the bandpass filter as shown in FIG. 3, the characteristic curve of the bandpass filter is Ta (FIG. 4). The band-pass filter generally has a center wavelength of a light transmission band, which is defined by an intermediate value of a half-value spectrum with respect to normal incidence as a reference, and the wavelength of the light La to be detected (the light emitted from the light source 11). Is set to coincide with the wavelength λ0). Therefore, when the light is incident perpendicularly to the bandpass filter like the light La, the light having the wavelength λ 0 can be detected well in the light receiving element 22. On the other hand, when the light is incident on the bandpass filter at an incident angle θ as in the light Lb shown in FIG. 3, the characteristic curve of the bandpass filter is shifted to the short wavelength side as shown in Tb (FIG. 4). The center wavelength is λ1.

  Here, when the wavelength shift amount at the incident angle θ is Δλ, Δλ = λ0−λ1. When the band-pass filter is formed as a single layer, it is expressed as λ1 = λ0 · cos θ, and the wavelength shift amount Δλ increases as the incident angle θ increases. Even when the band-pass filter is formed in multiple layers, the wavelength shift amount Δλ increases as the incident angle θ increases.

  In the present embodiment, a bandpass filter 23 that is set in advance assuming the wavelength shift amount Δλ is used. FIG. 5 is a diagram showing a characteristic curve T1 of the bandpass filter 23 used in the light receiver 20. As shown in FIG. In the present embodiment, as shown in FIG. 5, the center wavelength λ2 of the light transmission band of the bandpass filter 23 is set to be longer than the wavelength λ0 of the light to be detected. In other words, by setting the center wavelength λ2 of the bandpass filter 23 in advance to the longer wavelength side than the detection target wavelength λ0, even if the incident angle θ of the light incident on the bandpass filter 23 increases, the detection target wavelength The light of λ0 can be guided to the light receiving element 22 satisfactorily.

  Further, the band-pass filter 23 is set to have a transmittance equal to or higher than the predetermined value V even when light having a predetermined wavelength λ0 is perpendicularly incident on the band-pass filter 23. In other words, the band pass filter 23 is configured to transmit light having a predetermined wavelength λ0 to be detected even when no wavelength shift occurs. The predetermined value V is an arbitrary value set on the basis that light detection can be performed with high accuracy in the light receiving element 22.

  By forming the bandpass filter 23 as described above, the light receiving element 22 can detect light of the predetermined wavelength λ0 well at the time of vertical incidence, and even if the incident angle with respect to the bandpass filter 23 is increased, The light receiving element 22 can detect light having the predetermined wavelength λ0 satisfactorily. For this reason, it is possible to increase the angle of view (field-of-view range) of the light receiver 20 in the light projecting / receiving device 1, and to measure a three-dimensional shape of a relatively large subject 9 even if the light projecting / receiving device 1 is downsized. become.

  The center wavelength λ2 of the bandpass filter 23 is preferably determined based on the maximum incident angle θmax of light incident on the bandpass filter 23. Specifically, assuming that the wavelength shift amount Δλmax is incident on the bandpass filter 23 at the maximum incident angle θmax, the center wavelength λ2 of the bandpass filter 23 is more than a half of the wavelength shift amount Δλmax and on the long wavelength side. It is preferably set. That is, in this case, λ2 ≧ λ0 + Δλmax / 2.

  Further, the half-width H (see FIG. 5) of the bandpass filter 23 is also preferably determined based on the maximum incident angle θmax of light incident on the bandpass filter 23. Specifically, the half width H of the bandpass filter 23 is preferably set to be larger than the wavelength shift amount Δλmax when entering the bandpass filter 23 at the maximum incident angle θmax. That is, in this case, H ≧ Δλmax.

  For example, the full width at half maximum H is set to a value obtained by adding the wavelength shift amount Δλmax to the full width at half maximum H ′ when wavelength shift is not considered (that is, H = H ′ + Δλmax). Here, the full width at half maximum H ′ without considering the wavelength shift is, for example, the full width at half maximum of a conventional bandpass filter, and is the full width at half maximum of the characteristic curve T10 shown in FIG. In this way, by setting the half width H to H = H ′ + Δλmax, a bandpass filter that exhibits a substantially uniform transmittance from a state where no wavelength shift occurs to a state where the wavelength shift is maximized. 23 can be obtained.

  By setting the center wavelength λ2 and the half-value width H as described above, the light having the predetermined wavelength λ0 can be guided to the light receiving element 22 even when the incident angle to the bandpass filter 23 is increased. When it is desired to increase the angle of view of the light receiver 20, the maximum incident angle θmax with respect to the bandpass filter 23 is obtained based on the angle of view, and the center wavelength λ2 and the half wavelength satisfying the above conditions are determined based on the maximum incident angle θmax. By using the bandpass filter 23 having the value width H, it is possible to perform good detection at a desired angle of view.

  In order to most effectively reduce the influence of ambient light, the minimum value within the range included in the above condition may be selected for each of the center wavelength λ2 and the half-value width H.

  As described above, in the light projecting / receiving device 1 of the present embodiment, the light receiver 20 is provided with the bandpass filter 23 having the characteristic curve T1 of FIG. Light with a predetermined wavelength λ0 can be detected satisfactorily. FIG. 6 is a diagram showing a wavelength shift when the bandpass filter 23 in the present embodiment is used. In FIG. 6, the characteristic curve T2 of the band-pass filter 23 when perpendicularly incident on the light receiver 20 transmits light of a predetermined wavelength λ0 to be detected satisfactorily. And when it injects into the light receiver 20 from the diagonal direction, and the incident angle with respect to the band pass filter 23 will be about 30 degrees, the characteristic curve of the band pass filter 23 will shift from T2 to T3. And also in the characteristic curve T3, the band pass filter 23 transmits the light of the predetermined wavelength λ0 to be detected satisfactorily.

  Therefore, in the light projecting / receiving device 1 of the present embodiment, even when light having the predetermined wavelength λ0 is incident on the light receiver 20 from an oblique direction and the incident angle with respect to the bandpass filter 23 is increased, the bandpass filter 23 Light is transmitted well, and the light receiving element 22 can detect light having a predetermined wavelength λ0. Therefore, the light projecting and receiving device 1 can detect light of the predetermined wavelength λ0 with a wider angle of view than before, and can widen the measurement region by widening the angle of view.

<Second Embodiment>
Next, a second embodiment will be described. Also in this embodiment, the detailed configuration of the light projecting / receiving device 1 is the same as that described above, and the configuration shown in FIGS. 1 and 2 is also common in this embodiment. The light emitting / receiving device 1 of the present embodiment is different from the first embodiment described above in the characteristics of the bandpass filter 23 provided in the light receiver 20, which will be described in detail below.

  In light passing through a light receiving optical system 21 provided in the light receiver 20, a phenomenon called shading generally occurs. That is, shading is a phenomenon in which the image surface illuminance decreases as the distance from the optical axis to the periphery on the image surface is reduced. As the distance increases, the amount of light decreases. In addition to the cosine fourth law, shading may occur due to characteristics unique to the optical system.

  In the light receiver 20 of the light projecting / receiving device 1, light incident in an oblique direction from the peripheral portion of the visual field range follows the peripheral portion of the light receiving optical system 21, and the light amount is reduced due to the shading described above. Therefore, the amount of light received by the light receiving element 22 is significantly different between light that is perpendicularly incident on the light receiver 20 substantially in line with the optical axis and light that is obliquely incident from the periphery of the visual field range. Become.

  Therefore, in the present embodiment, a configuration example is shown in which shading correction is performed by the bandpass filter 23 so that the amount of light received by the light receiving element 22 is substantially uniform between the position near the optical axis and the peripheral portion.

  FIG. 7 is a diagram illustrating a characteristic curve T4 of the bandpass filter 23 used in the light receiver 20 in the present embodiment. Also in the present embodiment, as shown in FIG. 7, the center wavelength λ2 of the light transmission band of the bandpass filter 23 is set to be longer than the wavelength λ0 of the light to be detected. In other words, by setting the center wavelength λ2 of the bandpass filter 23 in advance to the longer wavelength side than the detection target wavelength λ0, even if the incident angle θ of the light incident on the bandpass filter 23 increases, the detection target wavelength The light of λ0 can be guided to the light receiving element 22 satisfactorily.

  Further, the band-pass filter 23 is set to have a transmittance equal to or higher than the predetermined value V even when light having a predetermined wavelength λ0 is perpendicularly incident on the band-pass filter 23. In other words, the band pass filter 23 is configured to transmit light having a predetermined wavelength λ0 to be detected even when no wavelength shift occurs. Here again, the predetermined value V is an arbitrary value set based on the fact that light detection can be accurately performed in the light receiving element 22.

  Furthermore, the center wavelength λ2 and the half width H of the bandpass filter 23 in the present embodiment are set under the same conditions as in the first embodiment. As a result, the same effects as those of the first embodiment can be obtained in this embodiment. That is, even when light having a predetermined wavelength λ 0 is incident on the light receiver 20 from an oblique direction and the incident angle with respect to the band pass filter 23 is increased, the band pass filter 23 transmits the light well, and the light receiving element 22. Can detect light having a predetermined wavelength λ0.

  Further, in the light projecting / receiving device 1 of the present embodiment, the characteristic curve T4 of the bandpass filter 23 has a high light transmittance on the long wavelength side and a light transmission on the low wavelength side in the light transmission band as shown in FIG. The rate is set to be low. And it sets so that the transmittance | permeability may become high gradually from the short wavelength side to the long wavelength side. For this reason, as the incident angle to the bandpass filter 23 increases, the transmittance of the predetermined wavelength λ0 gradually increases as the characteristic curve T4 of the bandpass filter 23 shifts to the lower wavelength side.

  FIG. 8 is a diagram showing a wavelength shift when the band-pass filter 23 in the present embodiment is used. In FIG. 8, a characteristic curve T5 of the bandpass filter 23 when vertically incident on the light receiver 20 transmits light of a predetermined wavelength λ0 to be detected at about 50%. And when it injects into the light receiver 20 from the diagonal direction, and the incident angle with respect to the band pass filter 23 will be about 30 degrees, the characteristic curve of the band pass filter 23 will shift from T5 to T6. In the characteristic curve T6, the band-pass filter 23 transmits light of the predetermined wavelength λ0 to be detected at about 80%.

  By attaching the band-pass filter 23 to the light-receiving element 22, the light incident substantially coincides with the optical axis of the light-receiving optical system 21, and the light incident perpendicularly to the band-pass filter 23 is relatively low of about 50%. The light passes through the band-pass filter 23 with the transmittance and is guided to the light receiving element 22. In contrast, when the light enters the bandpass filter 23 from the periphery of the visual field range of the light receiver 20 through the periphery of the light receiving optical system 21 at an incident angle of about 30 °, the light has a relatively high transmittance of about 80%. The light passes through the bandpass filter 23 and is guided to the light receiving element 22. Since the amount of light passing from the periphery of the visual field range of the light receiver 20 to the periphery of the light receiving optical system 21 is reduced by the above-described shading, the bandpass filter 23 transmits light in the vicinity of the optical axis with a small decrease in light amount with low transmittance. By transmitting light with a large reduction in light amount and guiding the light to the light receiving element 22, the light amount detected by the light receiving element 22 is uniform in the vicinity of the optical axis and its peripheral part. Adjusted to

  Note that the low transmittance on the short wavelength side, the high transmittance on the long wavelength side, and the change curve from the low transmittance to the high transmittance in the light transmission band are based on the shading phenomenon caused by the light receiving optical system 21 and are caused by shading. It is preferable to set so as to eliminate the influence.

  The band-pass filter 23 is configured as described above, and the above-described band-pass filter 23 is attached to the light-receiving surface of the light-receiving element 22 in the light receiver 20, so that light with a predetermined wavelength can be detected well with a wide angle of view. In addition, the influence of shading of the light receiving optical system 21 can be eliminated, and light with a uniform light amount distribution can be guided to the light receiving element 22. Therefore, according to the light projecting / receiving device 1 of the present embodiment, the measurement area can be widened by widening the angle of view, and uniform light can be received over the entire surface of the light receiving element 22, thereby achieving more stable light detection. Is possible.

<Modification>
Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described content.

  For example, in the above description, the mode in which the band-pass filter 23 is attached to the light receiving surface of the light receiving element 22 is shown, but the present invention is not limited to this. The band pass filter 23 may be inserted at an arbitrary position in the optical path of the light received by the light receiving element 22 in the light receiver 20. If the bandpass filter 23 is inserted at an arbitrary position in the optical path, the same effect as described above can be obtained.

  Moreover, in the above, although the case where the light projector 10 of the light projecting / receiving device 1 was configured to emit the strip-shaped light L1, the light projector 10 may emit other pattern light. FIG. 9 is a diagram illustrating examples of some pattern lights emitted from the projector 10. FIG. 9A shows a case where the band-shaped pattern light is projected onto the subject as described above. FIG. 9B is a diagram showing pattern light for forming dot patterns at equal intervals in two vertical and horizontal directions. In the case of the pattern light in FIG. 9B, the projection position of each dot is displaced according to the surface shape of the subject, and the three-dimensional shape of the subject can be measured by detecting the displacement. FIG. 9C is a diagram showing pattern light forming a cross pattern. The projector 10 may project any of the pattern lights shown in FIGS. 9A to 9C onto the subject. Further, a pattern other than the pattern light shown in FIGS. 9A to 9C may be projected onto the subject.

  Further, in the above, an example of the light projecting / receiving device 1 in which the projector 10 and the light receiver 20 are integrally formed is shown. However, the light receiving device 20 is a light receiving device formed separately from the projector 10. Also good. In the above, the case where the projector 10 and the light receiver 20 constitute a three-dimensional camera for measuring the three-dimensional shape of the subject 9 is exemplified, but the present invention is not limited to this. For example, a photoelectric switch or the like The configuration provided with the bandpass filter 23 can also be applied to the light receiver of the non-contact type sensor, and the angle of view of such a light receiver can be made larger than before.

It is a perspective view which shows the whole structure of a light projector / receiver. It is a figure which shows the internal structure of a light projector / receiver. It is a figure which shows the light which injects into a light receiver (light-receiving device). It is a figure which shows the wavelength shift of a band pass filter. It is a figure which shows the characteristic curve of the band pass filter in 1st Embodiment. It is a figure which shows the wavelength shift in 1st Embodiment. It is a figure which shows the characteristic curve of the band pass filter in 2nd Embodiment. It is a figure which shows the wavelength shift in 2nd Embodiment. It is a figure which shows the example of pattern light. It is a figure which shows the characteristic of a general band pass filter.

Explanation of symbols

1 Light Emitting / Receiving Device 10 Light Emitting Device 20 Light Receiving Device (Light Receiving Device)
21 light receiving optical system 22 light receiving element 23 band pass filter

Claims (8)

A light receiving device for detecting light of a predetermined wavelength,
A light receiving element that receives light and performs photoelectric conversion;
A light receiving optical system for guiding incident light to the light receiving element;
A band-pass filter inserted in an optical path of light received by the light receiving element;
With
The bandpass filter has a center wavelength of a light transmission band set longer than the predetermined wavelength, and transmits light of a predetermined value or more when light of the predetermined wavelength is perpendicularly incident on the bandpass filter. A light receiving device characterized by showing a rate. The light receiving device according to claim 1,
The center wavelength of the bandpass filter is longer than half the wavelength shift amount of the bandpass filter that occurs when light of the predetermined wavelength is incident on the bandpass filter at a maximum incident angle. A light receiving device that is set to The light receiving device according to claim 2,
The light-receiving device, wherein a half-value width of the band-pass filter is set to be larger than the wavelength shift amount. The light receiving device according to any one of claims 1 to 3,
The bandpass filter is set such that the light transmittance for the predetermined wavelength increases as the incident angle when the light of the predetermined wavelength enters the bandpass filter increases. apparatus. A projector that converts light having a predetermined wavelength emitted from a light source into a predetermined pattern light and projects the light onto a subject, and a reflected light from the subject on which the pattern light is projected by the projector via a light receiving optical system. A light receiving and receiving device that receives light by a light receiving element,
In the light receiver, a band pass filter is inserted in an optical path until the reflected light is guided to the light receiving element,
The band-pass filter has a center wavelength of a light transmission band set to a longer wavelength side than the predetermined wavelength, and when the reflected light of the predetermined wavelength is perpendicularly incident on the band-pass filter, A light projecting / receiving device characterized by exhibiting transmittance. In the light projecting and receiving device according to claim 5,
The center wavelength of the bandpass filter is longer than half the wavelength shift amount of the bandpass filter that occurs when light of the predetermined wavelength is incident on the bandpass filter at a maximum incident angle. The light projecting / receiving device is set to The light projecting / receiving device according to claim 6,
The light projecting / receiving device, wherein a half-value width of the band-pass filter is set to be larger than the wavelength shift amount. The light projecting / receiving device according to any one of claims 5 to 7,
The projection is characterized in that the bandpass filter is set so that the light transmittance for the predetermined wavelength increases as the incident angle when the light of the predetermined wavelength enters the bandpass filter increases. Light receiving device.

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